Mantis #7858: DeleteSceneObject done slightly differently. ProcessEntities now checks whether the objects have been deleted and, if so, sends an extra kill object packet, in order to compensate for potential race conditions encountered by the first one.

Note: I still cannot reproduce this problem, but I was able to emulate it by adding an artificial delay on ProcessEntities, which did, indeed, result in objects not being deleted. This fix fixed my emulated scenario.

OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs

@@ -357,7 +357,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// All manipulation of this set has to occur under an m_entityUpdates.SyncRoot lock
         ///
         /// </value>
-//        protected HashSet<uint> m_killRecord;
+        protected List<uint> m_killRecord;
 
 //        protected HashSet<uint> m_attachmentsSent;
 
@@ -509,7 +509,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             m_entityUpdates = new PriorityQueue(m_scene.Entities.Count);
             m_entityProps = new PriorityQueue(m_scene.Entities.Count);
             m_fullUpdateDataBlocksBuilder = new List<ObjectUpdatePacket.ObjectDataBlock>();
-//            m_killRecord = new HashSet<uint>();
+            m_killRecord = new List<uint>();
 //            m_attachmentsSent = new HashSet<uint>();
 
             m_assetService = m_scene.RequestModuleInterface<IAssetService>();
@@ -4005,6 +4005,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             OpenSim.Framework.Lazy<List<EntityUpdate>> terseUpdates = new OpenSim.Framework.Lazy<List<EntityUpdate>>();
             OpenSim.Framework.Lazy<List<EntityUpdate>> terseAgentUpdates = new OpenSim.Framework.Lazy<List<EntityUpdate>>();
 
+
             // Check to see if this is a flush
             if (maxUpdates <= 0)
             {
@@ -4033,9 +4034,19 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 {
                     SceneObjectPart part = (SceneObjectPart)update.Entity;
 
-                    if (part.ParentGroup.IsDeleted || part.ParentGroup.inTransit)
+                    if (part.ParentGroup.inTransit)
                         continue;
 
+                    if (part.ParentGroup.IsDeleted)
+                    {
+                        // Don't send updates for objects that have been marked deleted.
+                        // Instead send another kill object, because the first one may have gotten
+                        // into a race condition
+                        if (!m_killRecord.Contains(part.ParentGroup.LocalId))
+                            m_killRecord.Add(part.ParentGroup.LocalId);
+                        continue;
+                    }
+
                     if (part.ParentGroup.IsAttachment)
                     {   // Someone else's HUD, why are we getting these?
                         if (part.ParentGroup.OwnerID != AgentId && part.ParentGroup.HasPrivateAttachmentPoint)
@@ -4270,6 +4281,16 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
 
             #endregion Packet Sending
+
+            #region Handle deleted objects
+            if (m_killRecord.Count > 0)
+            {
+                SendKillObject(m_killRecord);
+                m_killRecord.Clear();
+            }
+            #endregion
+
+
         }
 
         // hack.. dont use

OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs

@@ -1987,6 +1987,7 @@ namespace OpenSim.Region.Framework.Scenes
         {
             // We need to keep track of this state in case this group is still queued for backup.
             IsDeleted = true;
+            HasGroupChanged = true;
 
             DetachFromBackup();
 
@@ -2010,7 +2011,13 @@ namespace OpenSim.Region.Framework.Scenes
                                 if (!IsAttachment
                                     || AttachedAvatar == avatar.ControllingClient.AgentId
                                     || !HasPrivateAttachmentPoint)
+                                {
+                                    // Send a kill object immediately
                                     avatar.ControllingClient.SendKillObject(new List<uint> { part.LocalId });
+                                    // Also, send a terse update; in case race conditions make the object pop again in the client,
+                                    // this update will send another kill object
+                                    m_rootPart.SendTerseUpdateToClient(avatar.ControllingClient);
+                                }
                             }
                         }
                     });

OpenSim/Region/Framework/Scenes/SceneObjectPart.cs

@@ -5390,9 +5390,6 @@ SendFullUpdateToClient(remoteClient, Position) ignores position parameter
 
         public void SendTerseUpdateToClient(IClientAPI remoteClient)
         {
-            if (ParentGroup.IsDeleted)
-                return;
-
             if (ParentGroup.IsAttachment
                 && (ParentGroup.RootPart != this
                     || ParentGroup.AttachedAvatar != remoteClient.AgentId && ParentGroup.HasPrivateAttachmentPoint))